1. Field of the Invention
The present invention relates to a fiber-reinforced polyolefin resin composite and to a molded article obtained from the same. In particular, this present invention relates to a fiber-reinforced polyolefin resin composite having an improved durability under circumstances of contact with metal and a molded article obtained from the composite.
2. Description of the Related Art
Polyolefin resin is in wide use as a general purpose resin because it is excellent in moldability and chemical resistance and has a low specific gravity. However, it is not always satisfactory in respect of mechanical strength and heat resistance and hence is rather restricted in its use. As a means for ameliorating such shortcomings and improving the mechanical strength of polyolefin resin such as rigidity and impact strength, it is already known to incorporate fillers, fiber, or the like into the resin. In industrial practice, fiber-reinforced polyolefin resin composites have been produced by mixing short fibers, such as chopped strands, with polyolefin resin and granulating the mixture with a kneader, but their mechanical strengths have not yet been fully satisfactory.
Accordingly, some attempts have been made to increase the mechanical strength greatly by using fiber of large fiber length. JP-A-3-121146 discloses a method for producing a long-fiber-reinforced polyolefin resin composite using a pultrusion process, the method comprising a step of impregnating continuous fiber strands with molten polyolefin resin while the fiber strands are being pulled, thereby incorporating, into the resin, 5-80% by weight (based on the total weight) of fibers arranged substantially in parallel each other. Mechanical properties, e.g. rigidity and impact strength, were improved by formed articles of long fiber-reinforced polyolefin resin composites produced by using such pultrusion molding methods.
Up to now, polyolefin resin has a problem that when it is applied to uses in which it contacts directly with metal, it becomes susceptible to thermal oxidative degradation, resulting in lowered durability. Long-fiber-reinforced polyolefin resin composites also have the same problem and, even when using conventional techniques which have been applied for formed articles of short-fiber-reinforced polyolefin resin composites produced by melt kneading, enhancement in durability under circumstances of contact with metal is still insufficient. Therefore, further improvement has been eagerly awaited.
An object of the present invention is to provide a fiber-reinforced polyolefin resin composite having an improved durability under circumstances of contact with metal and a molded article obtained from the composite.
After extensive study, the present inventors found that the above problems can be solved by a fiber-reinforced polyolefin resin composite and a molded article obtained from the same, the composite comprising a polyolefin resin (component (A)), fibers (component (B)), and a heavy metal deactivator (component (C)), the ratio of the weight of component (A) to the weight of component (B), (component (A)/component (B)), being within a specific range, the ratio of the weight of component (C) to the combined weight of components (A) and (B), (component (C)/[component (A)+component (B)]), being within a specific range, wherein in the composite substantially all the component (B) have lengths within a specific range. Resultantly, they completed the present invention.
That is, the present invention provides a fiber-reinforced polyolefin resin composite comprising the following components (A), (B) and (C), the ratio of the weight of component (A) to the weight of component (B), (component (A)/component (B)) being from 20/80 to 95/5, the ratio of the weight of component (C) to the combined weight of component (A) and component (B), (component (C)/[component (A)+component (B)]), being from 0.001/100 to 5/100, wherein in the composite substantially all the component (B) have lengths of 2 mm or more,
(A): polyolefin resin,
(B): fibers,
(C): heavy metal deactivator.
In addition, the invention also provides a molded article obtained from the above composite.